Ocean acidification is the increase in ocean acidity due to increased atmospheric CO₂ produced by human activities. As ocean acidity is predicted to more than double by 2100, organisms that can easily adapt may have an advantage when dealing with such rapid environmental changes. One method of adaptation is RNA editing. RNA editing is a posttranscriptional modification of the RNA molecules generally accomplished by adenosine deaminase acting on RNA. RNA editing exists in many organisms, but RNA edits are substantially more common in cephalopods, especially nonsynonymous edits. In this study we looked for changes in RNA editing levels in gill tissue of Octopus rubescens exposed to elevated CO₂. Three octopuses were kept in closed aquaria with an average pCO₂ of 1517±254 μatm, and the other three octopuses kept in closed aquaria with an average pCO₂ 735±47 μatm for two weeks. Then their gill tissues were collected for mRNA extraction and sequencing. Editing sites were found by aligning mRNA and gDNA of individual Octopus rubescens to their consensus transcriptome and finding locations where there are mismatches between the mRNA reads and the transcriptome as well as between the gDNA reads and the transcriptome. Differential edits were verified using poisoned primer extension assays.